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更新ing 14. mfs master 热备方案:
本帖最后由 shinelian 于 2010-02-05 13:11 编辑
更新ing
14. mfs master 热备方案:
前2天问了mfs作者关于 性能测试和灾难恢复这2块的情况,如下是回复,随信还附了mini how to :
Hi!
We are very happy that you are a user of MooseFS! Also thank you very much
for promoting the system in China!
Regarding the Distaster Recovery please read the mini how which I attach -
you can easily change the metalogger machine to be the master server.
Regarding performance tests - we have not done any extensive tests. And we
are happy that people from open source community like you contribute to it
and fill the gap.
We are preparing our new website and we would like to put there
descriptions of installed MooseFS systems all over the world. Could you
write more about your architecture? What is your master server? How many
chunkservers do you have? What is the total space used by you? And so on
and so on - the more details, the better.
Kind regards
Michał Borychowski
MooseFS Support Manager
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Gemius S.A.
ul. Wołoska 7, 02-672 Warszawa
Budynek MARS, klatka D
Tel.: +4822 874-41-00;
Fax : +4822 874-41-01
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How to prepare a fail proof solution with a redundant master?
A redundant master functionality is right now not a built-in functionality. But this subject is for us very crucial because we know how important this is and we receive lots of requests about it from many sources.
master的冗余能力目前还不是一个原生或者内建的功能,但这对我们来说是一个非常关键的课题,因为它是非常重要以及近来从许多地方受到了大量关于此问题的询问。
It is important to mention that even in MooseFS v 1.5.x edition it is relatively easy to write a scripts set which would quite automatically start a backup master server and in 1.6.x it is even simpler. The whole process of switching to the backup server would take less than a minute.
特别重要的,在moosefe1.5.x 系列已经可以通过编写脚本来自动的启动一个备援的master,在1.6.x系列则更为简单。切换到备援master的整个过程会花掉不到一分钟的时间。
It is enough to use for example Common Address Redundancy Protocol (http://www.openbsd.org/faq/pf/carp.html, http://en.wikipedia.org/wiki/Common_Address_Redundancy_Protocol). CARP allows that there exist two machines with the same IP in one LAN - one MASTER and the second BACKUP.
So you can set up IP of mfsmaster on a CARP interface and configure the master machine to be used as MooseFS main master. On the backup machine you also install mfsmaster but of course you do not run it.
Versions 1.6.5 and above contain a new program "mfsmetalogger" which you can run on whatever machine you wish. The program gets metadata from master - every several hours (by default every 24 hours) gets a full metadata file and on current basis a complete change log.
If you run an earlier version of MooseFS than 1.6.5 it is enough to set up several simple scripts run regularly from cron (eg. every one hour) which would backup metadata file from the main master "PREFIX/var/mfs/metadata.mfs.back".
You also need an extra script run continuously testing the CARP interface state which in case if this interface goes in a MASTER mode would get two or three newest "changelog" files from any chunkserver (just by using "scp"), would also start "mfsmetarestore" and then "mfsmaster". The switch time should take approximately several seconds and along with time necessary for reconnecting chunkservers a new master would be fully functional in about a minute (in both read and write modes).
We also plan to add option to run master in read-only mode - which would be the best option for running the backup machine. This would secure the system against potential desynchronization of the two master machines and the need of merging all the changes to the main master which took place on the backup master. |
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